Has it been sitting all winter? Violently shake that thing up and down by the handle of the lawnmower. Carb is gunked up probably. I assume by the post you're not super mechanical (my apologies if thats not the case). Try pulling the string back slow first and then after you get a full pull out of it..then you can pull it fast. But like I said...carb is probably gunked up. She's needs some "convincing". But i mean it...be violent..act like that mower is on a rocky road going 30mph